Drawing medium and method of making the same



M. D. MCMINTOSH DRAWING MEDIA AND METHOD oF MAKING THE SAME Aug. 5, 1947l Filed Nov. 6. 1943 MAURICE D. MlNTosr-i.

Patented Aug. 5, 1947 DRAWING MEDIUM AND METHOD OF MAKING THE SAME Maurice D. McIntosh, Cleveland Heights, Ohio, assigner to Louis S. Sanders, Shaker Heights,

Ohio

Application November 6, 1943, Serial No. %,269

11 Claims. l

This invention relates, as indicated, to drawing media and tcmethods of making the same.

A primary object of the invention is to provide media `which are not only useful for preparing mechanical and engineering drawings, but which may also be effectively used as photographic transparencies for the reproduction of such drawings in the form of prints of various kinds, such as blue prints, black and white prints, Ozalid prints and the like.

Another object of the invention is to provide a medium of the character described which is transparent or translucent and which bears on both surfaces thereon, patterns which are also of a transparent or translucent character, and which may be chemically developed to provide shading for drawings executed on such medium.

A further object of the invention is to provide a medium of the character described in which the pattern on one surface may be geometrically related to that on the other surface, or may be entirely unrelated to and independent of the latter.

A still further object of the invention is to Drovide a medium of the character described which bears on one surface thereof a plurality of patterns of a transparent or translucent character,

one of the patterns being developable by a developer solution capable of developing said pattern only and all of the patterns being developable by a developer solution capable of developing all of the patterns collectively.

A still further object of the invention is to provide methods of preparing such drawing media.

Other objects and advantages will be apparent during the course of the following description, taken in connection with the accompanying drawings, wherein Fig. 1 is a fragmentary view of a drawing medium, showing line patterns thereon in undeveloped condition;

Fig. 2 is a view similar to Fig. l, but showing the development of one of the patterns.

Fig. 3 is a view similar to Fig. 2, but showing the development of both patterns;

Fig. 4 is a view similar to Fig. l, but showing a dot pattern on one side of the medium;

Fig. 5 is a View similar to Fig. 4, but showing the development of the dot pattern, and

Fig. 6 is a view showing a photographic transparency made in accordance with the invention.

Referring more particularly to the drawings, Fig. 1 shows a hase sheet l which is substantially transparent or translucent, and which may be 2 an ordinary sheet of tracing paper cr tracing cloth, such as is commonly used by draftsmen and is capable o-f transmitting actinic rays,

On one surface of the base sheet l, I print a pattern, consisting in this instance, of closely spaced parallel lines 2 of a chemical compound, the pattern being also substantially transparent or translucent, and capable of transmitting actinic rays, but being capable of chemical development to a state of either complete opacity or of limited transmissibility wherein only nonactinic light rays are transmitted thereby.

On the other surface of the base sheet i, I print a second pattern, consisting, in this instance, of closely spaced parallel lines of a chemical cornpound 3, the pattern being similar in all respects to the pattern 2, that is to say, it is substantially transparent or translucent, and capable of transmitting actinic rays, but capable of chemical development to a state of either complete opacity or of limited transmissibility wherein only nonactinic light rays are transmitted thereby.

The lines 3, as shown in Fig. l, extend at right angles to the lines 2.

These patterns may be printed by means of a printing ink which is prepared in the following manner.

The following solutions are first prepared:

Solution No. 1

Solution No. 2

Parts by weight Water 750 Nitric acid (specific gravity 1.42) 30 Mercure-us nitrate 270 Solution No. 2 is poured slowly into Solution No. l, Solution No. l being agitated continuously and at high speed during the pouring operation.

This results in the precipitation of insoluble mercurous chloride in an extremely iine condition on the glue-glycerol base, so that when it is applied to the base sheet, as by printing to form the patterns 2 and 3, it is itself largely transmissible of actinic rays beca-use of its extremely fine state of division and complete lack of color.

After the patterns have been printed with the ink prepared in the foregoing manner, the base sheet is permitted to dry and is then run through a bath consisting of ethyl alcohol and 15% formalin, which serves to coagulate the glue and insolubly fixed the patterns in situ.

The sheet as thus prepared constitutes the drawing medium of my invention, and as such, is extremely useful in preparing mechanical and engineering drawings from which photo-print reproductions are to be made with the original drawing serving as a photographic transparency.

In using such medium, the ink or pencil drawing will be executed on one surface of the medium, and after it is completed, those areas of the surface or drawing which require a line shading will be developed, as indicated by the area A in Fig. 2, that is to say, the mercurous chloride lines forming the pattern 2 will be made opaque to actinic rays. This development may be effected by application to the mercurous chloride pattern of an aqueous solution or 3% thiourea,

Il it is desired to provide a crossmhatch shading for portions of the drawing, as for example, in the area B in Fig. 3, the pattern 2 will nrst be developed in such area, and the sheet then turned over and the pattern 3 developed, in such area, the patterns thus developed conjointly forming the cross-hatching shown within the area B in Fig. 3. The development of the pattern 3 will be facilitated by virtue of the fact that the sheet is transparent or translucent, so that the drawing and the previously developed pattern 2 can be easily seen through the sheet.

If it is desired to merely provide for the drawing line shading with the lines extending transversely to the lines of pattern 2, then it is only necessary to develop the lines of pattern 3 in areas where such line shading is desired, the lines forming pattern 2 remaining, in that case, undeveloped.

'I'he drawing or sheet, as thus shaded, may now be used as a photographic transparency in which the ink or pencil drawing and the developed portions of the pattern or patterns are opaque to actinic rays and the base sheet or sheet material and undeveloped portions of the pattern or patterns will transmit actinie rays. Such transparencies may be used for making reproductions on all ordinary types of photo-copying material, such as blue prints, black and white prints, Ozalid prints, Van Dyke prints, bichromate-gelatin and silver emulsions of the ordinary and orthochromatic types.

Although the invention has been described with reference to patterns consisting of closely spaced parallel lines, with the pattern on one surface of the sheet being geometrically related to that on the other surface thereof, it is to be understood that the patterns may be entirely individual and not related in any way. As for example, the pattern on one surface may consist of parallel lines, such as the pattern 2, while on the other surface, the pattern may consist of spaced dots, such as shown in Fig. 4 of the drawings, which may be developed, as indicated in the area C in Fig. 5.

Moreover, instead of using a mercurous chloride ink to form the patterns, and developing such patterns with thiourea, other combinations of chemically-developable patterns and developers may be used, among which the following may be mentioned:

l. An insoluble lead compound developed with soluble sulfide solution.

2. An insoluble copper compound developed with a soluble sulfide solution or a solution of a soluble salt of dialkyl dithiocarbamic acid such as sodium diethyl dithiocarbamate.

3. An insoluble nickel or cobalt compound developed with a soluble sulde solution.

In all cases, the insoluble compound should be precipitated on a colloidal base, such as glue, casein, albumin, or the like, in order to obtain the extremely ne state of division necessary for the transmission of light rays through the printed patterns. Any developable material used in forming the patterns must very largely transmit actinic rays in its undeveloped condition and transmit very few actinic rays in its developed condition.

As a base sheet, it is practicable to employ most cf the ordinary tracing papers and tracing cloths on the market, as well as most of the plastic sheets such as cellulose acetate, ethyl cellulose, Vinylite, etc.

As a modification of the invention, I may take a base sheet which is substantially transparent or translucent, such as that described, and, instead of applying patterns to both surfaces thereof, as described, may apply two separate patterns to the same side of the sheet, as described in my Reissue Patent No. 20,503. In such case, the patterns will be geometrically or otherwise related, and one of the patterns will be developable by a developer solution capable of developing said pattern only and both of the patterns being developable by a developer solution capable of developing both of said patterns collectively.

One of the patterns, in accordance with the invention, is applied to the surface of the transparent or translucent base sheet by means of a transparent or translucent mercurous chloride printing ink such as hereinbefore described, and capable of being developed by means of an aqueous solution of 3% thiourea. The other pattern, which is also preferably transparent or translucent, is printed by means of a printing ink which is prepared in the following manner.

The following solutions are first prepared:

.Solution No. 1

Parts by weight Solution N o. 2

Parts by weight Water 500 Lead acetate 320 Solution No. 2 is poured into Solution No. l, Solution No. 1 being agitated continuously during the pouring operation.

This results in the precipitation of very iinely divided lead sulphate on the glue-glycerol base, so that when it is applied to the base sheet, as by printing to form the second pattern, it is itself largely transmissible of actinic rays because of its extremely line state of division and lack of color.

Both patterns, i. e., the mercurous chloride and lead sulphate patterns, will then be collectively developable by means of sodium sulphide.

In Fig. 6, there is illustrated a photographic transparency prepared in accordance with the invention and consisting of a transparent base sheet 4 having on one surface thereof a mechanically or manually executed drawing 5 of the outline of a vase, shaded by shading or cross-hatch ing, similar to that shown in Fig. 3, and formed by successive development of line patterns on opposite sides of the sheet, as previously eX- plained.

It is to be understood that the forms of my invention herein Idescribed, are to be taken as preferred examples of the same, and that various changes may be resorted to without departing from the spirit of my invention, or the scope of the subjoined claims.

I claim:

1. A medium for use in preparing photographic transparencies, said medium comprising a transparent or translucent base sheet having a chemically-developable pattern on each of its surfaces.

2. A medium for use in preparing photographic transparencies, said medium comprising a transparent or translucent base sheet having chemically-developable line patterns on each of its surfaces.

3. A medium for use in preparing photographic transparencies, said medium comprising a transparent or translucent base sheet having a chemically-developable pattern on one of its surfaces, and a chemica1ly-developable pattern on the other surface thereof, said second pattern being geometrically related to the first pattern.

4. A medium for use in preparing photographic transparencies, said medium comprising a transparent or translucent base sheet having a chemically-developable line pattern on one 0f its surfaces, and a dot pattern on the other surface thereof,

5. The method of preparing a medium of the character described, which comprises providing a transparent or translucent base sheet, and applying to each of the surfaces of said sheet a chemically-developable pattern.

6. The method of preparing a medium of the character described, which comprises providing a transparent or translucent base sheet, and applying to each of the surfaces of said sheet a chemically-developable line pattern.

7. The method of preparing a medium of the character described, which comprises providing a transparent or translucent base sheet, applying to one surface of said sheet a chemically-developable pattern, and applying to the other surface of said sheet a chemically-developable pattern geometrically related to said rst pattern.

8. The method of preparing a medium of the character described, which comprises providing a transparent or translucent base sheet, applying to one surface of said sheet a chemically-developable line pattern and applying to the other surface of said sheet a chemica11y-developable dot pattern.

9. The method of preparing a photographic transparency, which comprises providing a transparent or translucent base sheet having a chemically-developable pattern on each of its surfaces, making a drawing on one of said surfaces, and developing portions of the patterns on each of said surfaces as an accompaniment for said drawing.

l0. A photographic transparency, consisting of a transparent or translucent base sheet having a mechanically produced drawing on one of its surfaces, and a chemically-developed pattern on the other surface thereof.

11. A photographic transparency consisting of a transparent or translucent base sheet having a mechanically-produced drawing on one of its surfaces, and chemically-developed patterns on both of its surfaces.

MAURICE D. MCINTOSH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,503 McIntosh Sept. 14, 1937 2,224,270 Sanders Dec. 10, 1940 2,240,945 SWaySland May 6, 1941 2,301,900 McIntosh NOV. l0, 1942 2,392,414 Sanders J an. 8, 1946 

